**3. Results**

#### **3.1 Midpoint (process-oriented) approach**

The midpoint approach presents the results of the impact categories in 2 tiers i.e., characterization and normalization. Normalization is based on the normalization factor which is the annual percentage of damage per capital which is the combination of different impact categories. The normalization factor is highly subjective and often set by method or software producers. Therefore, only characterization will be analyzed in details in this study to reduce uncertainties and also for proper understanding.

**Table 3** gives a better insight as the values are given based on the amount of impact for every 1 kg of OPC produced. Environmental impacts are categorized into 18 categories based on their contribution as seen. As said above, different impact categories have their own equivalence (units). The Global warming, terrestrial ecotoxicity and resource scarcity are the impact categories with the highest impacts. These Impact hotspots will further be analyzed to know the production process and substance causing these emissions and bringing about these environmental consequences.

Global warming brings about climate change which affects both human health and species. **Table 3** shows that for every 1 kg of OPC produced, 0.911 kg of CO2 equivalent is emitted during the production process. This implies that there is a very high tendency of global warming when cement as low as 1 kg is produced as a result of enormous CO2 that is emitted. This result is further analyzed to know the production process and substances causing this emission. Specification to process gives us information about the particular production process that contributes to the impact category and specification to substance gives the particular substance that is emitted or that affects the impact category. **Tables 4** and **5** show the specification to substance and specification to process respectively. While the former gives insight to the particular amount of CO2 emitted and the CO2 equivalent, the latter shows the particular production process that produces these emissions.

**Table 4** shows that 97.l% of CO2 is produced while less than 3% are other gases. **Table 5** shows that 85.6% of 97.1% CO2 seen as in **Table 2** was produced during clinker production phase of 1 kg of OPC that was produced. The specification to process of global warming in **Table 6** shows that 83.2% of clinker production brings about global warming.


*Life Cycle Assessment of Ordinary Portland Cement (OPC) Using both Problem… DOI: http://dx.doi.org/10.5772/intechopen.98398*

#### **Table 3.**

*Impact assessment table of 1 kg Portland cement using midpoint LCIA method.*


#### **Table 4.**

*Specification to substance of global warming.*


#### **Table 5.**

*Specification to process of carbon dioxide (fossil) in global warming.*
